The present invention relates to an anomalous condition detecting apparatus for a motor fan to be mounted on a vehicle for cooling engine cooling water or a medium for air conditioning.
A cooling motor fan to be mounted on a vehicle can not achieve its full function when the rotation of the cooling motor fan is stopped (a locked state) though this state is not wanted or when the operation of the cooling motor fan is in an over-loaded state (a half-locked state), because of a foreign material caught into the fan, for example. Therefore, it is necessary to take measures for checking from time to time whether the motor fan of the vehicle is in an abnormal state or note, and when an anomalous condition has occurred, for making this state to be known to vehicle occupants or for compulsively stopping the motor fan.
As an apparatus for detecting an anomalous condition such as a locked state or a half-locked state of a motor fan, there has been a device for detecting the rotation number of the fan by a magnetic or photo-electric pulse sensor or the like and for deciding that the motor fan is in an anomalous state when the rotation number is below a reference value. As a lock state detector, there is a one for detecting an excess current which flows during a locked time.